2022年第69回応用物理学会春季学術講演会

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一般セッション(口頭講演)

3 光・フォトニクス » 3.1 光学基礎・光学新領域

[22a-D315-1~6] 3.1 光学基礎・光学新領域

2022年3月22日(火) 10:00 〜 11:30 D315 (D315)

柚山 健一(大阪市立大)

10:30 〜 10:45

[22a-D315-3] Optical Binding Outside the Focal Spot Leads to Swarming of Gold Nanoparticles

〇(D)Chih-Hao Huang1、Boris Louis2,3、Roger Bresoli-Obach1,2、Tetsuhiro Kudo4、Rafael Camacho2,5、Ivan G. Scheblykin3、Teruki Sugiyama1、Johan Hofkens2、Hiroshi Masuhara1 (1.National Yang Ming Chiao Tung Univ., Taiwan、2.Ktholieke Univ. Leuven, Belgium、3.Lund Univ., Sweden、4.Toyota Tech. Inst., Japan、5.Univ. of Gothenburg, Sweden)

キーワード:Optical trapping, Optical binding, Gold nanoparticles

Previously, our group reported a large swarming assembly of 200 nm gold nanoparticles (Au NPs) formed by laser trapping at the glass/solution interface. The Au NPs in the swarms dynamically fluctuate while being spatially confined in a volume, indicating that the optical potential is expanded outside of the irradiated area of the incident laser.
In this work, we applied single particle tracking analysis to investigate the initial stage of the optical trapping and swarming of 400 nm Au NPs, tracing the origin of the optical potential expansion. As a result, correlated motion between particles is not only observed inside but also outside the laser focus. The external NPs show an expanding arc-shaped distribution with a characteristic half-wavelength inter-arc distance. The obtained results strongly support that optical binding can occur outside the irradiated area and extend its network through multiple scattering among more optically-bound NPs, leading to the dumbbell-shaped swarming assembly.